/* ==========================================================================
   Shared lesson stylesheet for the git-worktrees teaching workspace.
   Every lesson and reference document links this file. Tufte-influenced:
   generous measure, a real margin for asides, restrained palette.
   Designed to print cleanly to A4/Letter.
   ========================================================================== */

:root {
  --ink: #1a1917;
  --ink-soft: #55514b;
  --ink-faint: #8a847c;
  --paper: #fffdf9;
  --rule: #e3ded4;
  --accent: #8a3324;      /* oxide red — headings, marks */
  --accent-soft: #f4ece6;
  --code-bg: #f6f2ec;
  --ok: #2f6b4f;
  --warn: #9a6a00;
  --measure: 34rem;

  --serif: "Iowan Old Style", "Palatino Linotype", Palatino, "Book Antiqua",
           Georgia, serif;
  --sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui,
          sans-serif;
  --mono: "SF Mono", "JetBrains Mono", Menlo, Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --ink: #e8e4dd;
    --ink-soft: #a9a29a;
    --ink-faint: #7a746c;
    --paper: #161513;
    --rule: #33302b;
    --accent: #e0785f;
    --accent-soft: #2a211d;
    --code-bg: #1f1d1a;
    --ok: #7cc4a0;
    --warn: #d9a442;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0 auto;
  padding: 4rem 1.5rem 8rem;
  max-width: 58rem;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.0625rem;
  line-height: 1.62;
  font-kerning: normal;
  text-rendering: optimizeLegibility;
}

/* --- Masthead ----------------------------------------------------------- */

.masthead {
  max-width: var(--measure);
  margin-bottom: 3.5rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--rule);
}

.eyebrow {
  font-family: var(--sans);
  font-size: 0.6875rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 0.75rem;
}

.masthead h1 {
  margin: 0 0 0.5rem;
  font-size: 2.25rem;
  line-height: 1.15;
  font-weight: 600;
  letter-spacing: -0.015em;
}

.standfirst {
  margin: 0;
  color: var(--ink-soft);
  font-size: 1.1875rem;
  line-height: 1.5;
  font-style: italic;
}

/* --- Structure ---------------------------------------------------------- */

section { max-width: var(--measure); margin-bottom: 3rem; }

h2 {
  margin: 3.25rem 0 1rem;
  font-size: 1.375rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  line-height: 1.25;
}

h2 .num {
  display: inline-block;
  min-width: 1.6em;
  color: var(--accent);
  font-family: var(--sans);
  font-size: 0.8125rem;
  font-weight: 700;
  vertical-align: 0.28em;
}

h3 {
  margin: 2rem 0 0.6rem;
  font-size: 1.0625rem;
  font-weight: 600;
  font-family: var(--sans);
  letter-spacing: -0.005em;
}

p { margin: 0 0 1.1rem; }

a { color: var(--accent); text-decoration-thickness: 1px; text-underline-offset: 2px; }
a:hover { background: var(--accent-soft); }

strong { font-weight: 650; }

em.term {
  font-style: normal;
  font-weight: 650;
  border-bottom: 2px solid var(--accent-soft);
}

ul, ol { margin: 0 0 1.1rem; padding-left: 1.3rem; }
li { margin-bottom: 0.45rem; }

hr { border: 0; border-top: 1px solid var(--rule); margin: 3rem 0; max-width: var(--measure); }

/* --- Margin notes ------------------------------------------------------- */

.sidenote {
  float: right;
  clear: right;
  width: 15rem;
  margin: 0.3rem -18rem 1rem 0;
  font-family: var(--sans);
  font-size: 0.8125rem;
  line-height: 1.5;
  color: var(--ink-soft);
  border-left: 2px solid var(--rule);
  padding-left: 0.85rem;
}

.sidenote .label {
  display: block;
  font-weight: 600;
  font-size: 0.6875rem;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: 0.25rem;
}

@media (max-width: 1100px) {
  .sidenote {
    float: none;
    width: auto;
    margin: 1.25rem 0;
    background: var(--code-bg);
    border-left: 3px solid var(--accent);
    padding: 0.85rem 1rem;
  }
}

/* --- Code --------------------------------------------------------------- */

code {
  font-family: var(--mono);
  font-size: 0.875em;
  background: var(--code-bg);
  padding: 0.12em 0.36em;
  border-radius: 3px;
  word-break: break-word;
}

pre {
  background: var(--code-bg);
  border: 1px solid var(--rule);
  border-radius: 5px;
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-size: 0.8125rem;
  line-height: 1.65;
  margin: 0 0 1.25rem;
}

pre code { background: none; padding: 0; font-size: inherit; }

/* Terminal transcript: $ prompt lines vs output */
.term { position: relative; }
.term .cmd { color: var(--ink); font-weight: 600; display: block; }
.term .cmd::before { content: "$ "; color: var(--accent); font-weight: 700; }
.term .out { color: var(--ink-soft); display: block; }
.term .cm { color: var(--ink-faint); font-style: italic; display: block; }

figcaption {
  font-family: var(--sans);
  font-size: 0.8125rem;
  color: var(--ink-faint);
  margin: -0.75rem 0 1.75rem;
}

/* --- Callouts ----------------------------------------------------------- */

.callout {
  max-width: var(--measure);
  margin: 1.75rem 0;
  padding: 1rem 1.2rem;
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  border-radius: 0 4px 4px 0;
  font-size: 0.9375rem;
}

.callout p:last-child { margin-bottom: 0; }

.callout .label {
  display: block;
  font-family: var(--sans);
  font-size: 0.6875rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.4rem;
}

/* --- Diagram ------------------------------------------------------------ */

.diagram {
  max-width: var(--measure);
  margin: 2rem 0;
  padding: 1.5rem;
  border: 1px solid var(--rule);
  border-radius: 6px;
  background: var(--code-bg);
  overflow-x: auto;
}

.diagram svg { display: block; width: 100%; height: auto; }

/* --- Tables ------------------------------------------------------------- */

table {
  width: 100%;
  max-width: var(--measure);
  border-collapse: collapse;
  font-family: var(--sans);
  font-size: 0.875rem;
  margin: 0 0 1.5rem;
}

th {
  text-align: left;
  font-weight: 600;
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-faint);
  border-bottom: 1.5px solid var(--rule);
  padding: 0 0.75rem 0.5rem 0;
}

td {
  padding: 0.6rem 0.75rem 0.6rem 0;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
}

td code { font-size: 0.8125rem; }

/* --- Footer / nav ------------------------------------------------------- */

.lesson-footer {
  max-width: var(--measure);
  margin-top: 4rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--rule);
  font-family: var(--sans);
  font-size: 0.875rem;
  color: var(--ink-soft);
}

.lesson-footer h3 { margin-top: 0; }

.ask-teacher {
  max-width: var(--measure);
  margin: 2.5rem 0 0;
  padding: 1rem 1.2rem;
  border: 1px dashed var(--rule);
  border-radius: 5px;
  font-family: var(--sans);
  font-size: 0.875rem;
  color: var(--ink-soft);
}

.ask-teacher strong { color: var(--ink); }

/* --- Print -------------------------------------------------------------- */

@media print {
  :root {
    --paper: #fff; --ink: #000; --ink-soft: #333; --ink-faint: #666;
    --code-bg: #f5f5f5; --rule: #ccc; --accent: #000; --accent-soft: #f0f0f0;
  }
  body { padding: 0; font-size: 10.5pt; max-width: none; }
  .sidenote { float: none; width: auto; margin: 1rem 0; background: none;
              border-left: 2px solid #ccc; }
  pre, .diagram, .callout, .quiz { break-inside: avoid; }
  h2 { break-after: avoid; }
  .quiz-controls, .ask-teacher { display: none; }
  a { text-decoration: none; color: #000; }
  a[href^="http"]::after { content: " (" attr(href) ")"; font-size: 8pt; color: #666; }
}